04/23/2021
By Joanne Gagnon-Ketchen
Location: Contact Joanne Gagnon-Ketchen for link
“Reverberation mapping black hole accretion flows,“ Erin Kara, Assistant Professor of Physics, Massachusetts Institute of Technology
Abstract: Sitting at the heart of nearly all galaxies is a massive black hole, that, while typically 1000 times less massive than the galaxy in which it resides, has the potential to release enough energy via accretion of gas onto the black hole, to completely unbind the entire galaxy. Most of the power from an Active Galactic Nucleus (AGN) is released close to the black hole, and thus studying the inner accretion flow, at the intersection of gas inflow and energy outflow, is essential for understanding how black holes grow and affect galactic evolution. In the past decade, we have had a breakthrough in how we probe the inner accretion flow, through the discovery of X-ray Reverberation Mapping, where X-rays produced close to the black hole reverberate off inflowing gas. By measuring reverberation time delays, we can quantify the effects of strongly curved space time and the black hole spin, which is key for understanding how efficiently energy can be tapped from the accretion process. In this talk, I will give an overview of this field, and show how extending these X-ray spectral-timing techniques to transient accretion episodes is helping us probe the formation of X-ray coronae, jets and other relativistic outflows.
Bio: Erin Kara is originally from Bethlehem, Pennsylvania, and attended Barnard College, where she obtained a B.A. in physics with a minor in art history. After graduating in 2011, she moved to the United Kingdom on a Gates Cambridge Scholarship to study for a Masters and a PhD from the Institute of Astronomy at the University of Cambridge. In 2015, she was awarded a NASA Hubble Postdoctoral Fellow, which she took to the University of Maryland and NASA’s Goddard Space Flight Center. In 2018, she became the Neil Gehrels Prize Postdoctoral Fellow at the University of Maryland and joined the faculty of MIT as an Assistant Professor of Physics in July 2019.
Professor Kara is an observational astrophysicist, working to understand the physics behind how black holes grow and affect their environments. She has advanced a new technique called X-ray reverberation mapping, which allows astronomers to map the gas falling on to black holes and measure the effects of strongly curved spacetime close to the event horizon. She also works on variety of transient phenomena, such as tidal disruption events and Galactic black hole outbursts. She is a NASA Participating Scientist for XRISM Observatory, a joint JAXA / NASA X-ray spectroscopy mission, and co-chairs the supermassive black hole working group. She has authored more than 80 peer reviewed presentations and in 2019 was also awarded an Exceptional Scientific Achievement award from NASA.
Speaker Round Table: Please join the speaker for a round table discussion after Colloquium from 5 to 5:30 p.m.